How about something like this? I would leave the engine the way it is (I have the 6.5L TD) and take all that money and go with a hybrid system... Remove the transfer case and let the engine drive the rear axle only (add torque / rpm sensors and whatever adapter is needed), then take an EV motor, something like the Model S motor or the Ford Mach E, which measures about 22" x 13" x 14" generating about 281hp & 317ft-lb at 200lbs at around $4,000 (need to move some things around, like the catalytic converter, away from the transfer case and higher up in the tunnel where there is some unused space, relocate the muffler, maybe even lift the truck a few inches to get more room, etc.) and have it drive only the front axle for a higher total truck hp/ torque.
Dollar for dollar, electric has a massive advantage in terms of power density and efficiency and very soon, cost also.
ELUMINATOR™ MACH E ELECTRIC MOTOR |Ford Performance Parts
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This will also add the ability to recapture some of the diesel energy used to accelerate the truck's mass, during stopping, as the electric motor will act as a load on the front axle as it would partially recharge the batteries during stopping (some of the energy that currently is 100% lost as heat dissipated in the breaks to stop the truck's mass, would get recaptured into the batteries.
Of course, it would still need a few other things and a controller to match the two power systems distribution (that's where the torque/ rpm sensors come in).
Right now this may not look attractive, but in 1-3 years as the EV components costs are dropping so fast and the power density increases, this it will become an easier and less expensive way to add power.
I love the diesel sound and the overall truck feel, and I would also love to double the torque (I think the front & rear differentials can handle about 500 ft-lb each?) and this would be the way I would think to go while still preserving the truck's soul...just make it younger